Compaction apparatus



Feb. 23, 965 w. A. HERPICH ETAL 3,170,377

COMPACTION APPARATUS Filed June 10, 1959 5 Sheets-Sheet 1 INVENTORS WILL/AM A. HERP/Ch' HENRY C. FRENCH, JR.

ATTORNEYS A T TORNEKS' Feb. 23, 1965 w. A.HERPICH ETAL COMPACTION APPARATUS Filed June 10, 1959 5 Sheets-$1Mt 2 W. A. HERPICH ETAL COMPACTION APPARATUS Feb. 23, 1965 Filed June 10, 1959 INVENTORS ATTORNEYS WILLIAM A. HERP/CH BHENRJ C FRENC LVVMJ Feb. 23, 1965 w, HERPICH ETAL 3,170,377

COMPACTION APPARATUS Filed June 10, 1959 5 Sheets-Sheet 4 v 68 W l/O INVENTORS 05 [06 K H 1/ I16 F 5 WILLIAM A. HERP/CH iE- HENRY c FRENCH, JR.

BY M M7 4 ATTORNEYS Feb. 23, 1965 w. A. HERPICH ETAL COMPACTION APPARATUS 5 Sheets-Sheet 5 Filed June 10, 1959 INVENTORS W/LL/AM ,4 HERP/CH HENRY C. FRENCH JR 8;

ATTORNEYS 3,170,377 COMPACTION-APPARATUS William A. Herpich and Henry C. French, Jr., Knoxville,

Tenn., assignors to Dempster Brothers, Inc., Knoxville,

a corporation of Tennessee Filed June 10, 1959, Ser. No. 819,457

Claims. (Cl. 91-'169) Tenn.,

so that it will occupy a relatively smallvolu'rne. Then,

when the body is filled; with compacted refusefthe truck may be driven to a dump where charged fromthe body.

Compaction bodies of this type-usually include a large the refuse may be dis Uni ed ,states Patent 0 Patented 'Feb. 23, 1965 double-acting, multiple stage, hydraulic cylinder for mov ing'the packer head back and forth, and by providing" refuse chamber-extending longitudinally of the body. The

rear end of the chamber is closed normally by a rear door, but such door may be opened when it is desired to discharge-thecompacted refuse fromthe chamber, The

- front end of the refuse'chamber is bounded bya movable wall or packer head mounted in the body for longitudinal movements and driven by suitable hydraulic equipment. i

Refuse may be loaded into the refuse chamber through the top of the body at a location near its front end. Then, the packer head is caused to move rearwardly to compress and pack the material into the rear end portion of the chamber. 'After the packing stroke of the packer head, the packer head is moved forwardly to condition the apparatus forthe reception of another load of refuse through the top of the body.

This cycle normally is repeated at a number of dif with less attention from the operator of the apparatus.

'A more specific object of the invention is to provide an improved telescopic cylinder which can be retracted quickly and easily, so that it will be possible to reduce the time required for the-forward or idle stroke of the at the commencement of aretraction strokeis greater than. that available at any other time during the retraction stroke. With this constructionpthe force necessary for setting the parts in motionim'tially is available readily.

Yet another objectofthis invention is to provide automatic control means for causingt he packer head to move 1 through a complete compaction cycle without requiring any. attention from theoperator of the apparatus.

Another objectiof the inventionis to provide ah ydraulic system of, Such a construction that a single telenovel means for controlling the flow with respect to the cylinder. a

In the preferred embodiment of the invention, the double-acting hydraulic cylinder is so constructed that the hydraulic fluid for both extending'and retracting the cylinder enters and leaves the cylinder through the plunger end, that is, the small end of. the cylinder. Compaction of the load in the body is accomplished when the cylinder is extended to push the packer head rearwardly. This power stroke requires a rather large volume of hydraulic fluid, and in order that the fluid may flow as freely as possible, the passageways within the cylinderffor this fluid are relatively large. In contrast, only a small amount of power is required for the retraction of the packer head, and theoil pasages in the cylinderfor directing the fluid so as to retract the cylinder may berelativ'ely small.- a

It is particularly important that the oil passageway of hydraulic fluid through which oil may flow out of the cylinder duringretraction be free from obstructions. This has not been the case in the telescopic cylinders used heretofore in compaction bodies, and as a result the retract or return stroke of the packer head has always taken a substantial amount of time. Moreover, the back pressure in the hydraulic fiuid causes unnecessary power losses. The present invention overcomes these difiiculties by a novel arrangement of the flow passages within the hydraulic cylinder. ,7 V 1 The basic cycle of operations for the compaction body includes a rearward movement of the packer head, afor' packer head varies in accordance with the. amount of material in'the bodyitself. That is to say, .the packer head will move further when there is very little material in the body than when the body is nearly full. The controlling factor is the degree of compression of the material. The packer head moves rearwardly until the back pressure of the charge reaches some predetermined value. At this point, the compression stroke of thepacker head is terminated, and the packer head is moved forwardly again toward the front end of the body.

Thepresent invention contemplates a control mechanism by which an entire cycle of packer head operation may be carried out automatically. After a body of refuse has been inserted into the body, the operator trips the control mechanism manually, and then the control mechanism takes-over to direct the hydraulic fluid along paths whichwill cause the telescopic cylinder to extend until a predetermined back pressure is reached, and then move forwardly tothe front end of .thebody; where it remains scopic cylinder serves not only to move the packer head" but also to detect the degree of compression of the com} 7 i? pacted material, so'that the automatic control means requires no separate detector element. v

The foregoing objects may beaccomplished, according to the invention, by providing'a compaction: body with aatrest until the operator of the equipment again trips the'control mechanism. 1

This feature of the invention "makes it unnecessary for the operator of the equipment to utilize his judgment as to how far the packer head should go during eachcompaction stroke and it also makes more. time available to the operator for the accomplishment of his tasks; .After the operator'has tripped the control mechanism, he may leave the compaction body entirely to collect more refuse to be dumped into the' bodyr While he is vgone, the apparatus automatically goes through the compaction and the retraction strokes and comes to rest inrtheproperposb tion.

better understanding of the structure and operationof-the invention will be gained from a studyof the fol;-

lowing detailed description of certain embodiments thereof illustrated in the drawings, in which:

FIG. 1 is a side elevational view of a truck-mounted compaction body for handling refuse; L

FIG. 2 is a longitudinal cross sectional view of a three stagepdouble acting, hydraulic cylinder unit for use in the compaction body of FIG. 1, showing thepositions of the various parts when the cylinder unit is retracted;

FIG. 3 is a longitudinal cross sectional view of the. cylinder unit shown in FIG. 2, but illustrating the positions of the various parts when the cylinderunit is expanded; FIG. 4 is a transverse cross the line 44 in FIG. 3; A a

FIG. 5 is a diagrammatic view of the hydraulic system for operating the hydraulic cylinder unit connected to the packer headof the apparatus; i

FIG. 6 is an elevational view ofanautomatic control valve used in the system of FIG. 5; v a I FIG. 7 is a longitudinal cross sectional view of the control valve, takenalong the line 7 7 in FIG 6 and showing the parts in the positions they assume when the hydraulic cylinder unit is idle;

FIG. 8 is a view similar to FIG. .7, butshowing the parts in the positions they assume when the hydraulic sectional view taken along cylinder unit is being expanded; g

FIG. 9 is across sectional view similar to FIGS. 7 and 8, but illustrating the parts in the positions they assume when the hydraulic cylinder unit is being retracted;

FIG. 10 is a vertical cross sectional view of the confrol valve, taken along the line 10-16 in FIG. 9;

FIG. 11 is a vertical cross sectional view of the cont'rol valve, taken along the line 11-11 in FIG. 9; H 2

FIG. 12 is a longitudinal cross sectional view of another forrn of double acting hydraulic cylinder unit which may be used in the compaction body of FIG. 1, showing the parts in the positions they occupy when the cylinder is expanded; and

FIG. 13 is a longitudinal cross sectional view of the top half of the cylinder unit of FIG. '1Q, showing the parts in the positions they occupy when the cylinder is retracted. f g

The refuse handling equipment illustrated in FIG. 1 of the drawings is in the form of a truck 2 having a frame 4, wheels 6, a cab 8, and a refuse body 10. The apparatus also may include a front end loading mechanism 12 for raising detachable refuse containers 14 over the cab 8 and dumping them into the body 10.

Disposed within the body 10 is a packer head 16 mounted for longitudinal movementsrelative to the walls of the body 10. This packer head 16 actually forms the front wall of the refuse chamber in the body 10, Movemerits of the packer head 16 are brought aboutthrough operation of a hydraulic cylinder unit 18 pivotally con-. nected at 20 to the body 10 and pivotally connected at 22 to the packer head 16. Upon expansion of'the hydraulic cylinder unit 18, the packer head 16 moves rearwardly of the body 10 to compress or pack any material in the body between itsrear face and the rear door or wall of the body 10.

The normal sequence of operations performed by the apparatus shown in FIG. 1 will be evident. First, the

operator 'drives the truck 2 to the location o fa detachable container 14 which is to be emptied. The loader mechanism 12 lifts the container 14 to dumpits contents into the body 10 rearwardly of the packer head 16, and then returns the container 14 to' the ground. The charge'is compacted to the, desired degree-by moving the packer head '16 rearwardly until a predeterminedback' pressure is built up in the compressed' charge; Av return, or "for Ward, stroke of the packer head' 16-conditions the/appa ratus for the reception of the next charge.

1 This basic cycle may be repeated many timesbefo re' the body 10 is filled'to such an extent that it must be emp tied. When it is desired to empty the body 10, the vehicle is driven to a dump or the like, the rear door of the body 19 is opened, and the packer head 16 is moved all the way to the rear of the body It) so as to eject the material through the rear door of the body.

It will be observed that useful work is accomplished by the packer head 16 only during rearward strokes thereof. Both compaction and ejection-take place as the packer head 16 moves reaiwardly. Forward strokes or movements of the packer head 16 are idle strokes which serve merely to position the head 16 properly for the beginning of a new working cycle. Nevertheless, these g idle strokes of the packer head are brought about through the development of relatively high pressures in the hydraulic system. It is desirable that these forward strokes of the packer head 16 be carried out quickly and with a minimum consumption of power.

, It also will be observed from FIG. 1 that the rearward strokes of the packer head 16 are brought about by expansion of the hydraulic cylinder unit 18, whereas the forward strokes of the packer head 16- are broughtabout by contraction of the cylinderhydraulic unit 18. g In order that the hydraulic system may function rapidly and with small power losses during the retraction of the cylinder unit 18, this cylinder unit 18 has been provided with a novel arrangement of internal flow passages best illustrated in FIGS. 2, 3 and 4. v a

The cylinder unit 18 includes three cylinders 24,16,

and 23. The largest of these, i.e., cylinder 24, sometimes between the inner surface of the cylinder 24 and the.

outer surface of the cylinder 26. The interior wall of the cylinder 24 is recessed at 36 for receiving an O-ringdevice 38 which is forms a stop for a spacer 40 located between the cylinders 24 -and 26 and having an annular undercut portion 42 cm its interior surface providing'a longitudinally extending oil passage'or duct therein. A body of suitable packing material 44 preferably is located between the spacer 40 and the bushing 34. v

The intermediate cylinder 26 also is provided with a retainer 46, a bushing 48, a spacer 50 having a longitudinal oil passageor duct 52, an O-ring device 54 and a body of packing material 56. These components are similar to those carried by the larger outer cylinder124. At its innermost end, the intermediate cylinder 26 has secured thereto a piston member 58. The piston member 58 slides back and forthwith respect to the large cylinder or body 24 duringexpansion and retraction of the unit 13. Sealing ringstii) preferably are carried by the piston member 58 in the customary manner.

The smallest cylinder or ram 28 also is provided with a piston member 62 at its forward end. The pist member 62 carries the usual sealing rings 64 and slides.

backand forth with respect to the intermediatejcyli nder 26 during operation of the unit 18. Theouter'end of the ram 28 is substantially closed by a member 66 and .a fitting '68 secured thereto. These elements are provided with oil passageways 71B and 72'which communicate respectively with conduits 74 and 76.

Mounted within the ram cylinder 28 is an adapter member 78 having alarge longitudinal oil passageway 80 and having also a radialoil channel 82. The oil channel 82 is isolated fromthe main portion of the interior of th e interiornwall of the cylinder 28.

and68 and communicating with the passagef72. It is preferred that an oil seal tifi'be provided between the pip'e 8'6 and the adapter 78. 'A'retaining rir'i ggtlina'y be employed to holdthe adapterT/S inposition with respect to the cylinder '28.

When'it is desiredto expand the unit 18 fromthe condition shown in FIG. 2 tolthe condition shown in FIG. 3, oil is forced into. the unit 18 through theconduit 74 and the passage '70. It may pass readily from one end of the ram 28 to the other through the large opening 80 in the adapter 78, so that-the interior of the unit 18 will be filled rapidly. The oil then forces the cylinders 24 and 26 outwardly with respect to the innermost cylinder 28. This motion causes the packer head 16 of the apparatus shown in FIG. 1 to move rearwardly.

When it is desired to retract the unit 18 from the condition illustrated in FIG. 3 and bring it into the condition illustrated in FIG. 2, oil is forced into the unit through the conduit 76 and the passage 72. From the passage 72, the oil flows through the pipe 86 andinto the radial channel 82 in the'adapter 78. From the channel 82, the oil may flow through an aperture orport 92 in the wall of the cylinder 28.

With the cylinder unit .18; in the extended position shown in FIG. 3, the port 92 communicates with the longitudinal duct 52 in thespacer 50 carried by the end portion of the intermediate cylinder 26. This permits oil to flow'into the space between the spacer50 and the piston 62. Since thepiston 62 is fixed to the ram 28 .and the spacer 5 0 is .fixed to theintermediate cylinder 26, the ram 28"and the intermediate cylinder 26 move relative to each:

other under the influence of the pressure of the oil-passing through the relief or duct 52 in the sp-acerSO. This relative movement continues until the piston 62 on the ram 28 is brought into abutting relationship with respect to the piston 58 onv theinterrnediate cylinder 26.

Just beforeithe pistons 58 and '62 contact Yeac hiother,

however, the relative movement between the ram 28 and i the intermediate cylindcr 26 brings the piston .62 on the ram 218 beyond a port 94 in the wall of theintermediate cylinder 26. This relationshiPiS indicated best in FIGQZ of the drawings. 1 After theport94 has been brought into communication with the port 92, the oil from the inlet conduit 76 may flowinto the relief "or longitudinal channel 42 in the spacer lflcarried by the large cylinder or body 24 of theunit 18.

.. Again itwill be observed thatthe oil pressure acts upon a piston 58 carried by the intermediate cylinder-26 and a I spacer 40 carried'by theouter cylinder 24 to causerelativemovement between the intermediate cylinder 26 and the large cylinder 24. t This movement continues until the piston 58 on the intermediate cylinder 26 abuts against the endwall. 39 of the main cylinder or body: 24 of-the unit. Atthis moment, the retraction of the unit 18 iscomplete,

' and the parts .occupy the positions shown in FIG..2 of the usual intelescopic cylinder units of this general type, and frequently the; amount of oilrequired for the power stroke i is: as much .aseight times as. great asthe amountreq'n red for a, retraction stroke. v

complishedonly by moving a very large volume'ot oil out of =th'einterior;v oid in the unit 18. That is to. say a large enoutot the unitduring the retraction stroke. The speed y with which retraction can take'place, andthe power required for retraction, depend in large measure upon the resistance of the discharge flow path for .this-oil;

Thepresent invention represents; a significant achieve rnent'in i'ninimizingth'e resistance'of the flow path. fol-the ejection of the large bodyof oil within'ltheflcentral void of the unit 18., By reason ofthi s, .back pressure. is minis mized and thecylinder maybev retracted quickly andeasily. 7 Note that theccentralvoid'in the unitfl181shown in; FIGS.

2 and 3 is in substantially open communication with the outlet passage 7 0. Oilrnay flow freely from one cylinder to the next through the large openings in the pistons 58 and 62, and the oil also may flow freely'through the large The system for controlling the flow'of hydraulic fluid t0 and from the telescopic cylinder unit 18 is indicated diagrammatically in FIG. 5 of the drawings. This system includes an oil tank or reservoir 96, a pump 98 connected to the oil tank 96, a control valve connected to the pump, and a relief valve 102 interposed between the pump 98 and the control valve 100 to divert the flow from the pump directly into the oil tank 96 whenever the pressure at the control valve exceeds some predetermined valueaboye the normal working rangeof the system. Suitable conduit means are provided for connecting the various components of the; system together so that the hydraulic fluid may flow in the desired manner. 7 It will be observed that the conduits'74 and 76 leading into thecylinder'unit 18 are coupled to the control valve 100 of the system shown in FIG. 5. i p

c The control valve 100 has three basic positions or conditions. In one of these, the hydraulic fluid delivered by thepump; 98 is returned directly to theqoil tank 96 so that the cylinder. unit 18 will be idle or inactive. In a second condition of the control valve 100, the hydraulic fluid from the pump 98is delivered through the valve 100 to the conduit 74, and hydraulic fluid. may pass freely from the cylinder 18 through the conduit $7.6 andfthe valve more the oil'tank as. This second medium-er the 9 control valve is that which causes expansionfof the cylinder unit 18. A thirdcondition of the control valve 100 is one in which the hydraulic fluid is delivered from the pump 98. 7 through the control'valve 100 into the conduit 76 leading to the retract side of the cylinder;unit18., This third con packer head 16 of the refuse-handling apparatus to move throughtherequired strokes ,Withvery little attention from the operator of the apparatus. i c

The valve ltlttincludes a body.designated generally by'the numeral 104 which'rnay be made up of as many pieces as required. The particular body. construction 104 illustrated in the drawings is made up of three blocks 7 or units 1Q6, 108:and suitably secured together, but

.Itfollows also thatretraction of theunit-18 can be ac- I sageway-118 leading to two oil chambers and-122 v V V a c t adjacent the main cylinder '112 of the device. The shape 9 portion or oiLused in expanding the unit 18 must be drivvided is so LPOSltlQlled asftqfpermitthis actipn r Hydraulic fluidapassesiifrom "helcgntrol'view;100, he q a'n fifi' hr gh an pe 4i" zbpeu n *1 124'communicates with a passageway1126leadin'g to .aichamber IZS'adjacent the mainbore-112,of-thedevice.

this number may be varied as desired. Within the body 104, there is a main cylinder or bore 112 for slidably receiving a main piston or plunger designated generally by the numeral 114. handle 116 '(FIG 6),,is pro tor manually shifting the plunger 114 along the bore I II, V J

Hydraulic fluid from-the pump 98 may'enter the valve .ltitlthrough an opening 116 communicating with apasof the ,chambers 1 20 and 122 is, not a"critical factor. However, it; is desirable that they'be of such a nature that oil may pass readily trom'thenr throughthe-main piston 114] bore- 11 2 of the valveiwhenever the spoolf or The opening 124 also communicates with a radial pas sage leading to another: chamber 132 adjacent the main bore 112. Hence, it will be seen that the oil may leave the valve 100 through the opening 124 if oil under pressure is admitted to either of the chambers 128 or- 132.

In order for oil to flow to or from the control valve 100 through the conduit means 74 communicating with the cylinder unit 13, the body 104 of the control valve 100 is provided with a radial passage 134 communicating with an annular chamber 136 surrounding the main bore 112 of the device. I This how path is shownclearly in FIG. 10 of the drawings.

Similarly, oil may flow to or from the control valve 100 through the conduit 76 by passing throughia radial passage 138 communicating with an annular chamber 140 surrounding the main bore 112. This flow path is illustrated in FIG. 11.

During operation of the hydraulic system, oil may flow between adjacent 'ones of the chambers 120, 122, 128, 132, 136 and 140, only to the extent permitted by a pair of reduced portions 142 and 144 in the piston 114 of the valve. The large portions 146, 148 and 150 of the plunger 114 are of substantially the same diameter as the bore 112. Whenever one of these large portions of the plunger 114 is located between adjacent ones of the chambers 120, 122, 128, 132, 136 and 140, it serves to block'anyfiow of the oil between such chambers.

V The position of the plunger 114 illustrated in FIG. 7 of the drawings is that which corresponds with the idle condition of the hydraulic circuit. Oil from the pump 98 enters the control valve 100 through the opening 116, and moves through the passage 118 into the chamber 122. Since the reduced portion 142 of the plunger 114 of the valve'is located in the space'betweenthe chamber 122 and the adjacent chamber 128, the oil flows from the chamber 122 through the bore 112 to thecharnber 128. The chamber 128 communicates with the outlet 7 opening 124 through the passage 126, so that oil may flow directly from the chamber 128 into the conduit lead- 100 to move the plunger 114 as far to the right (FIGS.

6-9) as is possible. Thisposition is that in which the enlarged portion 150 of the plunger 114 abuts against the right end of the main bore 112 in the body 104, as illustrated in FIG. 8. r

It will be observed that this movement of the plunger 114 brings the reduced portion 142 thereof into the space between the chambers 132 and 140, and also brings the reduced portion 144 thereof into the spacebetween' the chambers 120 and 136. This makes it possible for'oil flowing into the opening 116 from the pump 98 to pass outwardly from the valve 100 through the conduit 74. It also makes it possible for the oil to flow into the valve unit 100 through the conduit 76,-because the fluid chamber 140 leading to the conduit 76 is in "open communication with the outlet opening 124 of the device. Thus, any oil which must be ejected'from the cylinder unit 18 in order that the cylinder may expand will pass through the valve 100 and into the oil tank 96.

adjacent the right end of'the main bore 112 in the body 104. An adjustable relief valve 156 normally blocks the passage 152, but when the pressure rises to some predetermined amount, the relief valve 156 opens to permit the flow of oil through the passage 152 and into the chamber 154. A needle valve 158 preferably is disposed between the relief valve 156 and the chamber 154.

As the pressure builds up in the chamber 154, the main piston or plunger 114 of the control valve is urged to the left as viewed in FIGS; 7, 8 and 9. At this moment, there is a body of oil in the left end portion of the main cylinder or bore 112 which must be forced out of the cylinder by' the moving plunger 114 through a small chamber 160 communicating with the left end of the bore 112 anda passage 162 leading from the chamber 160 to the outlet opening 124 in the body 104. However, there is a needle valve. 164 in the passageway 162 which restricts the flow of the oil through the passage 162 so that the movement of the plunger'114 is a controlled movement, rather than a sudden shift to the left.

As the plunger 1 14 moves to the left from the position shown in FIG. 8 of the drawings, the inlet opening 116 connected to the pump 98 is uncoupled from the expand side of the cylinder unit 18 and coupled to the retract side thereof, while the outlet opening 124 connected to the oil tank 96 of the system is uncoupled from the retract side of the cylinder unit 18 and coupled to the expand sroe.

" The manner in which this result is accomplished will be apparent from a comparison of FIGURES 8 and 9. Note that in FIG. 8 the reduced portion 144 of the plunger 114 is so located as to permit flow between the chambers and 136, and that the reduced portion 142 of the plunger 114 is so located as to permit flow between the chamhers and 132. In this condition of the control valve 100, oil from the pump 98may flow through the conduit 74 into the central void of the cylinder unit 18, and oil may flow from the cylinder unit '18 through the conduit 76 to the oil tank 96. v

[The flow pattern achieved when the plunger 114 is in the position shown in FIG. 9 is just theopposite of that achieved when the plunger is in the position shown in FIG. 8. In FIG. 9, the reduced portion 142 of the plunger 114 is so located that oil may flow from the chamher 122 int'ofthe chamber-140, and the reduced portion 144 of the plunger 114 is so located that the oil may flow from the chamber 136 into the chamber 132. Thus, the pump 98 is coupled to the conduit '76 leading to the retract side. of .the cylinder unit 18, while the conduit 74 leading from the exp-and sideof the cylinder unit 18 is coupled with the oil tank 96' so that the oil within the central void of the cylinder unit 18 may be exhausted to the oil tank during the retract stroke of the cylinder unit.

It is an important feature of the inventibn that the plunger1-14 of the control valve 100 stops automatically in the position shown in FIG, 9. Th controlled movement of the plunger 114 to the left from the positionshown in FIG. 8, due to the pressure of the oil in the chamber 154, continues only so 'long as the pressure in the inlet 116 is great enough to keep the relief valve 156 open. When the reduced portion 142 of the plunger 114 has moved far As the cylinder unit '18 expands, the pressure in the oil increases due to the load placed upon the hydraulic system when the refuse material is being packed between the packer head 16 and the-rear'wall of the compaction body. Hence, the cylinder unit 18 actually serves as ,a detector device forfsensing the degree of compaction of the refuse materiaL'because the oil pressure mustexceed the back pressure offered by the refuse. When theback I pressure reaches-a certain predetermined. value it is desirable that the expansion stroke of the cylinder unit 18 should be'terminated. i

n order to accomplish this resultautomatically, the control valve 100 is provided with a small oilpassageway 152 leading from the inlet opening llfi to 'aj'charnber 154 enough to the left to provide a substantial flow pa'thbetween the chambers .122 and 140, the pressure at the inlet 116 drops far below that required for holding. the relief valve 156 open, and there is no further tendency forfthe plunger 114 to move along the cylinder or bore 112. Thus, the position of the plunger 114 shown in FIG. 9 is a stable position, and the control valve ltltl -is effectiveautomatically. y v a When thecylinder unit 18 has-completed its contraction stroke, therejis no room for additional oil inside the retraction passageways therein, and the pressure at the control valve 100 builds pp again. When the pressure becomes great enough to open 1 the relief'valve 156,-oil again flows from the inlet 116through the passage 152 into the chamber 154 at'the right end of the bore 112. The increase in pressure at the right end of the bore 112 moves the plunger 114 on to the left'from the position shown in FIG.- 9 into the position shown in.FIG. 7. This movement brings the reduced 'portion'142 of the plunger 114 into a position such that the oil mayrflow directly from a the chamber 122 into thechamber 128, so as to couple the pump, 98 with the oiltanl; 96. In this position of vides a stop preventing outward movement of an annular bushing 190. A spacer member 192 is held in place on the interior of the cylinder 172 bymeans of an O-ring type of retainer 194 and a body of suitable packing mate'- rial 1 96 is.disposed in the space between the spacer'192 and the bushing 190. r

A port 198 is provided in the spacer 192 in position for communicating with the port 182 in the wall of the cylinder the parts, the cylinder unit 18 is idle, and the apparatus is ready for another compaction cycle whenever the oper ator desires'to-initiate such a cycle. All the operator has to do to start another cycle is to move the handle 116 so asto shift the plunger 114 goes through its entire compaction cycle; =That is to say, a the packer head 16 moves backrearwardly until the refuse,

is compacted to a'predetermined degree or pressure, and

then the packerhead 16 moves forwardly again and stops;

During this period, the operatorm'ay give his full attention to other matters, "He may leave the cab of the truck 2 to posit-ion other containers for cooperation with the frontend loader mechanism 12, or he may drive the truck to some new pick-up location; 7

It will be observedalso that thea'utomatic cyclejof the control valve 100 maybe interrupted by the operator at any time. If some unusual occurrenceshould take place during either the compaction or theretraction stroke "of the packer head 16'which would make it desirable to stop 1 further movements of the packer head 16, this can be acComplishedat oneeby shifting the handle 116 on the control valve 100 so as to'return the plunger 114 to the position shown in'FIG. 7. In this position of the plunger 114, the hydraulic system isidlei V I The same automatic eycle requiredfor compactionof the refuse material may be employed for ejecting the compacted refuse material from the rear end of the body I 10. After therear door of the body has been opened, the

cycle may be initiated so th'atthepacker head 16 will move rearwardly until. the hydraulic cylinder unit 18 is fully expanded. ,v At this point, pressure inthe inlet '116 of the valve control 100 will rise sufficientlvto' overpower the relief valve 156 and causdretraction-ofthe cylinder unit Another form of telescopic cylinder unit which may be used instead of the cylinder unit '18- in the compaction apparatus of FIG. 1 is illustrated in FIGS. 12 and 13 and 7 is designated generally by the numera1 170. The unit 1'70.

is made up of three cylinders or units 172,174 and 176, but r it will be understood that'the number-of stages employed may be varied'if desired; The principles of construction and operation illustrated in FIGS. 12 and 13 may be, adapted to units containing two or" more stages of cylinders.

'l The. large 'cylinder or base 172 i's closed at one end by a closure member 178; The'closure member 178 may be provided with a suitable fitting 180 through which oil may be admitted to the large void, in theinterior of'the cylinder hnit170'forexpai1ding the unit. Near its opposite end, thelarge cylinder or'base 172' is provided with a port-182 in its side wallcomrnunica'ting with a fitting le l zsccuredto theexterior of the cylinder 1 172. The fitting184 provides a: coupling for connectingv a conduit 186rwithathe-port'182 for retracting the cylinder ;unit'170.

.The outer end portion of the cylinder=172iis similar "inysome respects to the construction described above in i conn'ecti'on with FIGS; 2 a'nd3. A retainer 188. isithreadedly' connected withtheendfof the cylinder 172 and pro- 1:

172. The port 198 cormnunicates with a longitudinally extending duct 200 in the inner face of the-spacer 192 and also with a port 202 in the wall of the intermediate cylinder 174. V v

The intermediate cylinder 174 carries a'piston 204 on its inner end. Throughout a major portion ofthe length I of the intermediate cylinder 174, there is an internal cylin drical wall 2%, held in spaced relation with respect to the interior surface of the cylinder 174 by suitable spacers such as those designated by the numerals 208 and 210 in the drawings. "Thespace 212.between the intermediate cylinder 174 and the interior cylindrical wall 206 constitute an oil chamber or passageway in open communication with the port2tl2 in the wall of the cylinder 174.

At its outer end, thecylinder 174 is provided with a suitable retainer member;214,an annular bushing 216,

a body of packing material a 218, a spacer 220, i and a retainer 222. These parts are similar to the corresponding parts carried by the upper end portion of the large ,cyline 'der or base 172 of the'unit170;

Oil may flow from the passageway 212 through a port 224 in the wall 2%6'and' through an aperture'226 inlthe .spac'er 220. A longitudinal du'ct 228 in. the spacer22t1 permits the "oil from the aperture 226 to pass'to'apiston of the small cylinder Or ram ZStl'earried by the rear end 175 of the unit170. p

The outer end of the small cylinder or ram 176 is closed by a suitable plate 'or block member 232, which may be provided with any'suitable means for facilitating the attachment of the cylinder unit'17tl to the parts of the compaction apparatus with which it isto cooperate, A plate :234 is illustrated in- FIGJ12 in this connection. It will be observed that the'plate 2341s provided with a central aperture 236 by which the unit-175 may be piyotally connected-to a part with which itis to cooperate. A similar plate 238 may be secured to the closure 178 for the large 7 cylinder or base172 of the unit-170. 1 P

The flow paths for the hydraulic fl'uid When it is desired to retract the cylinder unit 170, oil

is admitted under pressure through the conduit 186 andthe port 182m the side wall of the large cylinder or base 172, and the conduit 18% communicating with the interior 'void in the unit 'is'connectedto the oil {reservoir or tank. -When thevarious passages in communication with the port 182 are filled with hydraulic fluid,*thepressure begins to build up. The force exerted by thispres'sure will be' a maximum against the piston 204 of the intermediate cylinder 174. This is so becaus thearea ofthe piston 204 in contact with the oilis'greater than the area of the piston 230 in contact with theioila Consequently, the retraction cycle will begin by a" movement of the piston 2M andlthei intermediate cylinder 174 to the left as viewed in K-FIGalZ. f 1". After the intermediate cylinder 174 has 'moved"all the way tothe left,'s'o.as to bring thepiston'gM into abutting relationship with respect to the closure 178, the hydraulic pressure willcause the sinall cylinder of ram l1 76and its J piston 230 to movetothe left also. This movement brings i i the parts into the positions-illustrated in FIG. 13..

within the cylin 'der unit 1711 now should be apparent. In order toexpand the cylinder unit 170 from the condition shown in FIG. 13

- into the condition shown in FIG. 12, oil is admitted through theopening 13% in the closure 178 for-the left end 1 of the large cylinder or base 1'72. This oil passes directly 7 into the large internal void of the cylinder unit .170 and is available to expand the unit in the ordinary way/ It willibe observed thatp during retraction, the maxi- 1 1 mum force becomes available at the very beginning of th stroke. This feature has significance in connection with the compaction apparatus as a whole. The greatest force required during the retraction stroke is that required to accelerate the packer head 16 in a rearward direction and to disengage it from the charge of refuse in the body. The variations in force which will be realized during use of the cylinder unit 170 illustrated in FIGS. 12 and 13 conform very wellv to the actual requirements of the compaction apparatus inthis respect. I a

It also will be observed in connection with FIG, 12 that the large central void within the unit 170 is in open and free communication with the conduit 186. Hence, during retraction of the unit 170, the large body of oil in the central void may pass freely out through the conduit 18%, and the back pressure developed during the retraction stroke will be minimized.

Although certain embodiments of the invention have been illustrated and described in detail, variations'and modifications will be obvious to persons skilled in the art. In particular, it will be apparent that various elementsof the illustrated constructions are capable of advantageous use in other combinations. For example, the automatic sequence valve shown in FIGS 6 to 11 need not be used to control a telescopic cylinderunit butfmay'be usedin combination with a single-stage, piston-type, double-acting cylinder unit, if desired. It is intended, therefore, that the foregoing description be considered as exemplary only and that the scope of this invention be ascertained from the following claims.

We claim:

1. Compaction apparatus comprising a body, a packer head movable back and forth in said body, a double-acting telescopic cylinder unit connected at on end thereof to-said body and connected to the other end thereof to said packer head for moving saidhead, said cylinder unit comprising a plurality of cylinders having'large central openings therein in free communication With each other, and fluid conduit menas connected to said ram-end of said cylinder unit for delivering'fiuid to the interior of the cylinders, the unit during expansion strokes thereof, and

separate fluid conduit means for delivering fluid to the space between the cylinders and out of communication 12 openings rapidly to expand the cylinder unit, conduit means connected to the exposed end of the largest endmost cylinder in the cylinder unit to deliver fluid to or from the central opening therein, said cylinders being mounted with respect to each other so as to leave closed spaces between the walls of adjacent cylinders into which hydraulic fluid may be forced to cause retraction of the cylinder unit, and conduit means fixed to and extending alongthe exterior of said endmost cylinder and communieating with the space between said endmost cylinder and the adjacent cylinder in the unit at a location near the opposite end of said endmost cylinder.

4. A double-acting telescopic cylinder unit comprising a plurality of cylinders mounted 'for telescoping movements relative to'each other, said cylinders having large central openings therein in free communication with each other so that a large volume of hydraulic fiuid may fill said openings rapidly to expand the cylinder unit, conduit means connected to the exposed end of the smallest endmost cylinder in the cylinder unit to deliver fluid to or from the central opening therein, said cylinders being mounted with respect ,to each other 'so as to leave closed spaces between the walls of adjacent cylinders into which by- ..draulic fluid may be forced to cause retraction of the cylinder unit, and conduit means fixed to andextending through the interiorof said endmost cylinder and communicating with the space between said endmost cylinder and the adjacent cylinder in the unit at'a location near the opposite end of said endmost cylinder.

5. A double-acting telescopic cylinderunit comprising a large cylinder having a large central opening therein, means closing the inner end of said'large cylinder, annular means fixed to the outer end of said large cylinder and projecting inwardly a short distance from the inner wall of said large cylinder, a ram cylinder mounted for sliding movement relative to said annular means and having an annular piston on its inner end in sliding contact with the inner wall of said large cylinder, said ram cylinder having 21 with the interior thereof for causing retraction strokes of 2. A double-acting telescopic cylinder unit comprising a plurality of cylinders mounted for telescoping movements relative to each other, said cylinders having large central openings therein in free communication with each other so that a large volume of hydraulic fluid may fill said openings rapidly to expand the cylinder unit, conduit means connected to the exposed end of an endmost cylinder in the cylinder unit to deliver fluid'to or from the central opening therein, said cylinders being mounted with respect to each other so as to leave closed spaces between the walls of adjacent cylinders into which hydraulic fluid may be forced to cause retraction of the cylinder unit, and conduit means fixed to said endmost cylinder and cornmuni cating with the space between said endmost cylinder and the adjacent cylinder in the unit at a location near the opposite end of said endmost cylinder. 7 p

3. A double-acting telescopic cylinder unit comprising'a plurality of cylinders mounted for telescoping movements so that a largevolume of hydraulic fluid may fill said large central opening therein infree communication with the large central opening in said large cylinder and being closed at its outer end,.said ram, cylinder also having a port in .its wall near the inner end thereof at a location 3 between said piston and said annular means, conduit means extending from the outer end of said ram' cylinder tral opening in said ram cylinder and for delivering hydraulic fluid to or from said conduit means in said ram cylinder.

I References-Cited in-the fileof this patent UNITED STATES PATENTS 2,188,956 Norin et al Feb. 6, 1940 2,388,755 McLeod Nov. 13, 1945 2,730,401 Rea Jan. 10, 1956 2,746,251 Ashton -TMayZZ, 1956 2,751,932 Stueland 2.. "June '26, 1956 2,800,234 Herpich et al. July 23, 1957 2,803,224 Wilson Aug. 20, 1957 2,854,958 'Woodet al on. 7,1958 2,874,720 Vahs Feb. 24, 1959 2,887,092 Brady May 19,1959 2,912,128 Kamin Nov. 10, 1959 2,985,147 'Rockwell 'May,23, 1961 FOREIGN PATENTS;

443,797 Great Britain/an--. Mar. 6, 1936 

1. COMPACTION APPARATUS COMPRISING A BODY, A PACKER HEAD MOVABLE BACK AND FORTH IN SAID BODY, A DOUBLE-ACTING TELESCOPIC CYLINDER UNIT CONNECTED AT ONE END THEREOF TO SAID BODY AND CONNECTED TO THE OTHER END THEREOF TO SAID PACKER HEAD FOR MOVING SAID HEAD, SAID CYLINDER UNIT COMPRISING A PLURALITY OF CYLINDERS HAVING LARGE CNETRAL OPENINGS THEREIN IN FREE COMMUNICATION WITH EACH OTHER, AND FLUID CONDUIT MEANS CONNECTED TO SAID RAM END OF SAID CYLINDER UNIT FOR DELIVERING FLUID TO THE INTERIOR OF THE CYLINDERS, THE UNIT DURING EXPANSION STROKES THEREOF, AND SEPARATE FLUID CONDUIT MEANS FOR DELIVERING FLUID TO THE SPACE BEWEEN TTHE CYLINDERS AND OUT OF COMMUNICATION WITH THE INTERIOR THEREOF FOR CAUSING RETRACTION STROKES OF THE CYLINDERS, SAID CYLINDER UNIT BEING SO CONSTRUCTED THAT A LARGE VOLUME OF FLUID MAY PASS FREELY INTO THE INTERIOR THEREOF DURING EXPANSION STROKES AND PASS FREELY FROM THE INTERIOR THEREOF DURING RETRACTION STROKES WHEREBY BACK PRESSURE DURING RETRACTION STROKES IS MINIMIZED. 